Load flow calculation is the fundamental analysis in electric power systems, and most of the load flow programs use well known Newton-Rapson (NR) method. The NR load flow programs normally converge within several iteration to the solution. However, nonconvergence within the specified number of iterations often occur, mainly caused by infeasible data. A lot of try and error effort will be needed to obtain the converged solution for it.

In this paper, a load flow solution method for infeasible conditions is proposed. The proposed method firstly judges whether the data is feasible or not in the iteration process, by using voltage stability index of each load node. For the infeasible case, appropriate load shedding will be taken to obtain the load flow convergence. The node of load shedding indicates the weak aria in the network from the viewpoint of the load flow convergence. The information can help the users to focus the modification or correction of the data, and to obtain the convergence easily.

The demonstrative application to both Kros & Kerner 11 node model and IEEE 118 node model are presented in order to verify the practicability of the proposed method.